Experimental study on the effect of magma intrusion and temperature on the pore structure of coal

The rich and intricate pore structure that coal possesses has a big impact on CBM engineering. We characterized the pore structure of coal samples at various distances from the magma intrusion point and at various temperatures using MIP, low-temperature nitrogen adsorption, and low-temperature carbon dioxide adsorption to study the thermal effect of temperature and magma intrusion on the pore structure of coal seams to better understand the properties of coal affected by temperature and thermal effect of magma. The results of the study prove that there are similar and different pore structures of coal samples at different distances from the magma intrusion point and at different temperatures. Heating and magma thermal effects have similar effects on coal samples in macroporous and micropore stages. The pore volume of coal samples increased with increased temperature or magma intrusion effect in the macroporous stage but decreased with increased temperature or magma intrusion effect in the microporous stage, with the magma thermal effect being more pronounced. While in the medium pore stage, the pore volume of coal samples increases and then decreases with the enhancement of magmatic intrusion influence, but the trend of decreasing development with the increase of temperature. This result makes a theoretical contribution to the selection of coal-bed methane utilization technology in the magmatic rock-influenced region.